The "Harry Potter" franchise will make first appearance at Comic-Con this year

San Diego, California (CNN) -- Only at San Diego Comic-Con, the annual gathering of self-proclaimed fanboys and fangirls, can an early screening of a movie feel like a rock concert, and then literally become one.

In a surprise on Thursday night, some audience members to the panel for "Scott Pilgrim vs. the World" --- in which star Michael Cera arrived in a Captain America costume --- were given the chance to see the entire movie early at a nearby theater.

The crowd cheered during the movie's opening credits and roared their approval whenever the title character landed a decisive blow while facing off with his new girlfriend's "evil exes."

The movie, based on a Japanese manga-inspired comic book, has a good possibility of appealing to comic book fans and gamers alike.

"It surpassed my expectations, and I'm a huge fan," said Gabriel Simon, after the screening, which ended with a performance by the band Metric, while cast members such as Anna Kendrick from "Up in the Air" rocked out in the balcony.

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Brittany Hernandez of La Jolla, California, is one of several who said the movie was the highlight of the convention so far. "I thought the movie was amazing. I saw the panel after the one for 'The Expendables.' Sylvester Stallone is hard to beat, but that was pretty awesome."

It's just one of many ways Hollywood studios are trying to get the most bang for their promotional buck among these hardcore filmgoers. Giving them a chance to see early footage is one thing, but some moviemakers are trying a more "immersive experience" to make sure that the fans have high praise for their top projects, especially when they post to their favorite social media site.

"Pilgrim" doesn't stop there, with an off-site area center where attendees can get custom-made T-shirts.

Not to be outdone, "The Green Hornet's" car, the Black Beauty, and the movie's "booth babes," known as the Green Hornettes are all over Comic-Con.

Con-goers can head up to another off-site location, Britt Reid's Garage, to catch a glimpse of the masked hero's vehicle of choice, and others owned by the Hornet.

"We tried to take risks and make something interesting, and also make something that is worth this amount of money," said the Hornet himself, Seth Rogen, gesturing towards the cars. "We went through a lot of different designs [for the Black Beauty] and ended up with basically the same design as the TV show. We just added bigger guns."

A Comic-Con veteran, Rogen prefers Marvel Comics over DC and, as for the convention itself, he says he "wishes it were a little bit more about the comics, actually."

If cars aren't your thing and you prefer your "immersive experiences" to be more on the techie side, "Tron: Legacy" has an app for that: an all-new version of the "Tanks" game from the Tron arcade can be downloaded onto iPhones.

There's also "Flynn's Arcade," returning to Comic-Con for the second year in a row. This year, there is a scavenger hunt of sorts on Twitter, where attentive fans can gain access to special events inside the arcade, which reveal secrets of the film, among other things.

Bruce Willis was also on hand to promote the upcoming comic book adaptation, "Red," though Oscar winner Helen Mirren may have stolen the show by talking about her first action role.

Speaking of action, the aforementioned Stallone was indeed there Thursday, pushing "The Expendables," along with just about every other action hero who isn't the governor of the most populous state in the union.

Another way to grab fans' attention is food, and Robert Rodriguez's upcoming "Machete" had a taco stand set up on Thursday night, along with an outdoor screening of new footage.

There are still a few more high-profile movies hoping to thrill the Comic-Con crowd. "Green Lantern" starring Ryan Reynolds, and the next two Marvel Comics adaptations, "Thor" and "Captain America: The First Avenger" still have their Hall H presentations coming up over the weekend. Visitors to the booths in the exhibitors hall had an early glimpse of Abin Sur, an alien from "Green Lantern," and both Thor's hammer and Cap's shield were on display.

Also, "Iron Man" director Jon Favreu is hoping that his third time's a charm at Comic-Con with "Cowboys & Aliens," which is still in production.

And believe it or not, "Harry Potter and the Deathly Hallows" will mark that successful movie franchise's first appearance in San Diego. Prior to the panel, fans are getting a look at the famous horcruxes as they will appear in the movie. At a convention where there is no such thing as too flashy, even the wildly-popular "Potter" might have to pull off every trick up his sleeve to avoid getting overshadowed.